Which Python GUI Library Fits Your Project? A Hands‑On Comparison of PyQt6, Dear PyGui, Flet, Textual & CustomTkinter

PyQt6 – Professional‑grade desktop GUI

Why use PyQt6

PyQt6 is the official Python binding for the Qt6 framework, which powers large‑scale applications such as Photoshop and Autodesk Maya. It provides C++‑level performance, a comprehensive widget set, and native cross‑platform support (Windows, macOS, Linux).

Installation

pip install PyQt6

Key features

True cross‑platform rendering with native look‑and‑feel.

Rich collection of widgets (tables, graphics view, web view, etc.) and a powerful layout system.

Qt Style Sheets enable CSS‑like theming.

Signal‑slot mechanism for type‑safe event handling.

Minimal example

import sys
from PyQt6.QtWidgets import QApplication, QWidget, QLabel, QPushButton, QVBoxLayout

app = QApplication(sys.argv)
window = QWidget()
window.setWindowTitle("PyQt6 quick start")
window.setGeometry(100, 100, 300, 200)

layout = QVBoxLayout()
label = QLabel("Welcome to PyQt6!")
button = QPushButton("Click me")

def on_click():
    label.setText("Button clicked!")

button.clicked.connect(on_click)
layout.addWidget(label)
layout.addWidget(button)
window.setLayout(layout)
window.show()
sys.exit(app.exec())

Practical notes

Learning curve: The signal‑slot system requires an initial investment, but once mastered development becomes rapid.

Styling: Qt Style Sheets allow you to apply modern, responsive designs without writing native CSS.

Layout management: Compared with Tkinter, Qt’s layout managers (QVBoxLayout, QGridLayout, etc.) are more expressive and handle resizing automatically.

Typical use cases: Professional desktop applications, data‑intensive tools, and any software that benefits from a native look on multiple OSes.

Dear PyGui – GPU‑accelerated lightweight GUI

What makes it different

Dear PyGui renders all UI elements via the GPU, giving frame‑rate‑smooth performance even for simple widgets. It is especially suited for real‑time monitoring dashboards where the UI must update dozens of times per second.

Installation

pip install dearpygui

Key highlights

Game‑engine‑style rendering pipeline (OpenGL/Vulkan) for minimal latency.

Built‑in data‑visualisation widgets such as progress bars, plots, and tables.

Very low CPU overhead – most work is off‑loaded to the GPU.

Data‑monitoring panel example

import dearpygui.dearpygui as dpg
import random, time

dpg.create_context()

def update_data():
    now = time.strftime("%H:%M:%S")
    cpu = random.randint(20, 90)
    mem = random.randint(30, 85)
    dpg.set_value("time_text", f"Time: {now}")
    dpg.set_value("cpu_bar", cpu / 100)
    dpg.set_value("cpu_value", f"CPU: {cpu}%")
    dpg.set_value("mem_bar", mem / 100)
    dpg.set_value("mem_value", f"Mem: {mem}%")

with dpg.window(label="System monitor", width=400, height=300):
    dpg.add_text("System status", color=(0,200,255))
    dpg.add_separator()
    dpg.add_text("", tag="time_text")
    dpg.add_text("CPU usage")
    dpg.add_progress_bar(tag="cpu_bar", width=300)
    dpg.add_text("", tag="cpu_value")
    dpg.add_spacing()
    dpg.add_text("Memory usage")
    dpg.add_progress_bar(tag="mem_bar", width=300)
    dpg.add_text("", tag="mem_value")
    dpg.add_spacing(count=2)
    dpg.add_button(label="Start", width=100)
    dpg.add_button(label="Stop", width=100)

dpg.set_frame_callback(10, update_data)

dpg.create_viewport(title='System monitor', width=420, height=350)

dpg.setup_dearpygui()

dpg.show_viewport()

dpg.start_dearpygui()

dpg.destroy_context()

Recommended scenarios

Internal tools that need fast, constantly updating visual feedback.

Automation scripts where a lightweight GUI is preferable to a full desktop framework.

Rapid prototyping of monitoring dashboards.

Flet – Build web, desktop & mobile UIs with pure Python

Python‑centric front‑end

Flet wraps the Flutter engine, allowing you to write a single Python codebase that can be deployed as a web app, a native desktop executable, or a mobile app. No JavaScript, HTML or CSS is required.

Installation

pip install flet

Core advantages

Write‑once, run on web, Windows, macOS, Linux, Android and iOS.

Material Design components (buttons, lists, dialogs, etc.) are available out of the box.

Responsive layout system automatically adapts to screen size.

File‑manager example

import flet as ft
import os
from pathlib import Path

def main(page: ft.Page):
    page.title = "Python file manager"
    page.theme_mode = ft.ThemeMode.DARK
    page.padding = 20
    cur_path = ft.Text(value=f"Current: {os.getcwd()}", size=16)
    file_list = ft.Column()

    def list_files():
        file_list.controls.clear()
        # parent directory entry
        if Path.cwd().parent != Path.cwd():
            file_list.controls.append(
                ft.ListTile(
                    leading=ft.Icon(ft.icons.FOLDER_OPEN),
                    title=ft.Text(".. (parent)"),
                    on_click=lambda e: change_dir(Path.cwd().parent)
                )
            )
        for item in sorted(Path.cwd().iterdir()):
            icon = ft.icons.FOLDER if item.is_dir() else ft.icons.INSERT_DRIVE_FILE
            color = ft.colors.BLUE_200 if item.is_dir() else ft.colors.WHITE
            file_list.controls.append(
                ft.ListTile(
                    leading=ft.Icon(icon, color=color),
                    title=ft.Text(item.name),
                    subtitle=ft.Text(f"Size: {item.stat().st_size:,} bytes" if item.is_file() else "Directory"),
                    on_click=lambda e, p=item: open_item(p)
                )
            )
        page.update()

    def change_dir(new_path):
        os.chdir(new_path)
        cur_path.value = f"Current: {os.getcwd()}"
        list_files()

    def open_item(p):
        if p.is_dir():
            change_dir(p)
        else:
            page.show_snack_bar(ft.SnackBar(ft.Text(f"Open file: {p.name}")))

    list_files()
    page.add(
        ft.Text("Python File Manager", size=24, weight=ft.FontWeight.BOLD),
        cur_path,
        ft.Divider(),
        ft.Container(content=file_list, height=400, border=ft.border.all(1, ft.colors.GREY_800), border_radius=10, padding=10),
        ft.Row([
            ft.ElevatedButton("Refresh", icon=ft.icons.REFRESH, on_click=lambda e: list_files()),
            ft.ElevatedButton("About", icon=ft.icons.INFO, on_click=lambda e: page.show_dialog(
                ft.AlertDialog(title=ft.Text("About"), content=ft.Text("File manager built with Flet"))
            ))
        ])
    )

ft.app(target=main)

Best suited for

Full‑stack Python developers who want to avoid front‑end tooling.

Quick prototypes that must be shareable as a web link.

Internal tools that benefit from multi‑platform deployment.

Textual – Modern terminal UI framework

Injecting a GUI feel into the terminal

Textual lets you create rich, interactive applications that run entirely inside a terminal. It works over SSH, consumes minimal resources, and supports CSS‑like styling for widgets.

Installation

pip install textual

Core benefits

Preserves the native terminal workflow – no X server required.

SSH‑friendly; the UI is rendered on the remote host and streamed as text.

Very low memory and CPU footprint.

Automation task manager example

from textual.app import App, ComposeResult
from textual.widgets import Header, Footer, Button, Label, Static
from textual.containers import Container, Vertical
import asyncio

class TaskManager(App):
    """Simple task manager UI"""
    CSS = """
    Screen { background: $surface; }
    .task-container { height: 1fr; border: solid $primary; padding: 1; }
    .success { color: $success; }
    .error { color: $error; }
    .running { color: $warning; }
    """

    def compose(self) -> ComposeResult:
        yield Header()
        with Container(id="main-container"):
            with Vertical(id="left-panel"):
                yield Label("Automation Task Manager", classes="title")
                yield Button("Run data clean", id="clean-data", variant="primary")
                yield Button("Generate report", id="generate-report", variant="success")
                yield Button("Backup DB", id="backup-db", variant="warning")
            with Vertical(id="right-panel", classes="task-container"):
                yield Label("Task status", classes="subtitle")
                yield Static("", id="status-display")
        yield Footer()

    def on_button_pressed(self, event: Button.Pressed) -> None:
        button_id = event.button.id
        status = self.query_one("#status-display")
        if button_id == "clean-data":
            status.update("[bold]Cleaning data…[/]")
            self.run_task(self.simulate_task, "Data clean", 3)
        elif button_id == "generate-report":
            status.update("[bold]Generating report…[/]")
            self.run_task(self.simulate_task, "Report", 2)
        elif button_id == "backup-db":
            status.update("[bold]Backing up DB…[/]")
            self.run_task(self.simulate_task, "Backup", 4)

    async def simulate_task(self, name: str, duration: int) -> None:
        status = self.query_one("#status-display")
        for i in range(duration):
            status.update(f"[bold]{name} ({i+1}/{duration})…[/]")
            await asyncio.sleep(1)
        status.update(f"[bold green]✓ {name} completed![/]")

if __name__ == "__main__":
    TaskManager().run()

Ideal scenarios

Server‑management utilities accessed via SSH.

CLI tools that need a richer, interactive interface without leaving the terminal.

Development helpers such as test runners, log viewers, or code inspectors.

CustomTkinter – Modernising classic Tkinter

Breathing new life into an old framework

If you already have Tkinter code or need to maintain legacy projects, CustomTkinter provides a Material‑Design look, dark‑mode support, and an improved layout system with minimal code changes.

Installation

pip install customtkinter

Core improvements

Material‑Design styling for all widgets.

Built‑in dark‑mode and theme switching.

More flexible layout containers (CTkFrame, CTkTabview, etc.).

Modern settings panel example

import customtkinter as ctk
import tkinter as tk
from tkinter import messagebox

class SettingsApp:
    def __init__(self):
        ctk.set_appearance_mode("dark")
        ctk.set_default_color_theme("blue")
        self.app = ctk.CTk()
        self.app.title("Modern Settings Panel")
        self.app.geometry("500x400")
        self.tabview = ctk.CTkTabview(self.app)
        self.tabview.pack(fill="both", expand=True, padx=20, pady=20)
        self.tabview.add("General")
        self.tabview.add("Appearance")
        self.tabview.add("About")
        self._setup_general()
        self._setup_appearance()
        self._setup_about()

    def _setup_general(self):
        tab = self.tabview.tab("General")
        self.auto_start = ctk.CTkSwitch(tab, text="Auto‑start on boot", command=self._auto_start_changed)
        self.auto_start.pack(pady=10, anchor="w", padx=20)
        self.auto_update = ctk.CTkSwitch(tab, text="Check for updates")
        self.auto_update.pack(pady=10, anchor="w", padx=20)
        ctk.CTkLabel(tab, text="Log level:").pack(pady=(20,5), anchor="w", padx=20)
        self.log_level = ctk.CTkComboBox(tab, values=["DEBUG","INFO","WARNING","ERROR"])
        self.log_level.pack(pady=5, anchor="w", padx=20, fill="x")

    def _setup_appearance(self):
        tab = self.tabview.tab("Appearance")
        ctk.CTkLabel(tab, text="Theme mode:").pack(pady=10, anchor="w", padx=20)
        self.theme_mode = ctk.CTkSegmentedButton(tab, values=["Light","Dark","System"], command=self._theme_changed)
        self.theme_mode.set("Dark")
        self.theme_mode.pack(pady=5, anchor="w", padx=20, fill="x")
        ctk.CTkLabel(tab, text="Color theme:").pack(pady=10, anchor="w", padx=20)
        self.color_theme = ctk.CTkComboBox(tab, values=["Blue","Green","Purple","Orange"])
        self.color_theme.pack(pady=5, anchor="w", padx=20, fill="x")

    def _setup_about(self):
        tab = self.tabview.tab("About")
        info = """
Modern Settings Panel
Version: 1.0.0
Author: Example
"""
        ctk.CTkLabel(tab, text=info, justify="left").pack(pady=20, padx=20)
        btn_frame = ctk.CTkFrame(tab)
        btn_frame.pack(pady=20)
        ctk.CTkButton(btn_frame, text="Check updates", width=100).pack(side="left", padx=10)
        ctk.CTkButton(btn_frame, text="Visit website", width=100).pack(side="left", padx=10)

    def _auto_start_changed(self):
        state = "ON" if self.auto_start.get() else "OFF"
        print(f"Auto‑start: {state}")

    def _theme_changed(self, value):
        mapping = {"Light": "light", "Dark": "dark", "System": "system"}
        ctk.set_appearance_mode(mapping[value])
        print(f"Theme switched to {value}")

    def run(self):
        self.app.mainloop()

if __name__ == "__main__":
    SettingsApp().run()

Migration advice

Replace Tkinter widgets with their CustomTkinter equivalents gradually.

Use the built‑in theme system to keep a consistent look across the application.

Leverage the same code structure – only the widget classes change.

Decision guide

PyQt6 – Best for full‑featured, native‑looking desktop applications. Learning curve medium, deployment moderate, aesthetic rating ★★★★★.

Dear PyGui – Ideal for high‑performance monitoring panels or lightweight tools that need GPU rendering. Easy learning, easy deployment, aesthetic rating ★★★★.

Flet – Perfect for Python‑only developers who want web, desktop, and mobile output from a single codebase. Easy learning, easy deployment, aesthetic rating ★★★★★.

Textual – Suited for terminal‑centric utilities, SSH‑friendly tools, and low‑resource environments. Medium learning curve, easy deployment, aesthetic rating ★★★.

CustomTkinter – Great for modernising existing Tkinter projects without a full rewrite. Easy learning, easy deployment, aesthetic rating ★★★★.

Recommendation strategy

If you need a web or multi‑platform app → choose Flet .

If you need a high‑performance monitoring dashboard → choose Dear PyGui .

If you are building a professional desktop tool → choose PyQt6 .

If you want to enhance a CLI utility with a richer UI → choose Textual .

If you have legacy Tkinter code and want a modern look → choose CustomTkinter .